Special Senses

Transduction

The process of converting a physical stimulus (light, sound, chemical) into an electrical signal (graded potential).

Receptor Potential

A type of graded potential in a sensory receptor.

Specificity

Receptors are "tuned" to specific energy types (e.g., photoreceptors only respond to light).

Adaptation

A decrease in sensitivity to a continuous stimulus (e.g., stopping noticing the smell of a room after being in it for a while).

Classifications By Stimulus

Mechanoreceptors (pressure), Thermoreceptors (temp), Photoreceptors (light), Chemoreceptors (chemicals), Nociceptors (pain).

Classifications By Location

Exteroceptors (outside body), Interoceptors (internal organs), Proprioceptors (skeletal muscles/joints).

Olfaction

Scent molecules must be dissolved in mucus to bind to receptors on olfactory cilia.

Olfactory Pathway

Receptors → Olfactory Bulb → Olfactory Tract →Olfactory Cortex (temporal lobe).

Taste buds are located within

papillae

5 Basic Tastes

Sweet, Sour, Salty, Bitter, and Umami (savory).

Cranial Nerves

Facial (VII), Glossopharyngeal (IX), and Vagus (X).

Lacrimal Apparatus

Lacrimal gland (produces tears) -→ Lacrimal canaliculi → Lacrimal sac → Nasolacrimal duct (into nose).

Parasympathetic

Sphincter pupillae muscles contract; pupil constricts (bright light).

Sympathetic

Dilator pupillae muscles contract; pupil dilates (low light/fight-or-flight).

Refraction

The bending of light as it passes through different media (cornea and lens).

Distant Vision

Ciliary muscles relax, suspensory ligaments tighten, lens becomes flat.

Close-up Vision

Ciliary muscles contract, suspensory ligaments loosen, lens becomes round/convex (Accommodation).

Emmetropia

Normal vision.

Myopia

Nearsighted - Eyeball too long; light focuses in front of retina.

Hyperopia

Farsighted - Eyeball too short; light focuses behind retina.

Astigmatism

Uneven curvature of cornea or lens.

Rods

Dim light, peripheral vision, high sensitivity, no color.

Cones

Bright light, high-definition, color vision (Red, Green, Blue).

Fovea Centralis

Center of the macula lutea; contains only cones and provides the sharpest vision.

Sound Collection

Auricle directs waves into the external acoustic meatus.

Sound Amplification

Waves vibrate the Tympanic Membrane, which moves the Ossicles (Malleus, Incus, Stapes). The stapes pushes on the Oval Window.

Sound Transmission

Pressure waves move through the fluid (perilymph) of the cochlea.

Sound Transduction

Fluid movement bends the hair cells (receptors) in the Organ of Corti, opening ion channels and releasing neurotransmitters.

Static Equilibrium

Monitors head position relative to gravity (linear acceleration).

Maculae

located in the Vestibule (Saccule and Utricle).

Dynamic Equilibrium

Monitors rotational movement.

Crista Ampullaris

located in the Semicircular Canals.